Resorcinol–formaldehyde (RF) has been known to cause red stains in the permanent teeth. While the use of this material in permanent teeth is controversial, there is little known about the effects of RF resin on primary teeth. A 6-year-old male and 9-year-old female (siblings) presented with a complaint of discoloration and mobility of the primary molars. On clinical examination, the teeth showed red discoloration as well as stains around restorations placed on them. Periapical radiographs revealed a radiolucency surrounding the affected teeth. On extraction, it was observed that the red discoloration extended to the tooth surface. Hematoxylin and eosin staining was done on two decalcified extracted teeth while two specimens (one from each patient) were subjected to gas chromatography–mass spectrometry (GC-MS) system (TRACE™ Ultra, Thermo Fisher Scientific, Waltham MA, USA). Histological examination showed signs of coagulative necrosis, while the GC-MS examination revealed the presence of a resorcinol spike confirming the initial diagnosis of RF therapy. The affected teeth were extracted and a long-span band and loop space maintainer placed in the younger child. The older child was observed for the eruption of the permanent tooth. RF resin can result in the discoloration and early exfoliation of primary teeth. This case report highlights the risks of using RF therapy in primary teeth.

Keywords: Primary teeth, pulp therapy, resorcinol–formaldehyde resin

How to cite this article:Althabit HO, Pani SC, Mosadomi HA, Ibrahim Z. The use of mass spectrophotometry to detect resorcinol–formaldehyde-induced discoloration and resorption of primary teeth: A report of two cases. Saudi J Oral Sci 2018;5:125-9

The pink discoloration and mobility of a primary tooth in a child are a disconcerting phenomenon usually attributed to internal resorption with or without dental trauma.[1] Tooth discoloration secondary to the use of endodontic materials has been reported in both primary and permanent teeth.[2],[3],[4] Pink or reddish discoloration due to the use of an endodontic material, though previously reported in permanent teeth, has seldom been observed in primary teeth.[5]

Resorcinol is a white powder which when mixed with formocresol produces a resinous mixture that has found extensive application in the field of adhesives.[6] In the 1970s, this compound was researched as a potential cariostatic agent due to its antibacterial properties.[7] The resin formed by the interaction of resorcinol with formaldehyde (RF), results in the necrosis of pulpal tissue, and therefore, was studied as a possible endodontic filling material in the 1980s.[8],[9] This led to the development of what has been described in the literature as resignifying therapy (RT).[8],[9],[10]

The concerns raised on the carcinogenic potential of formalin-containing materials (IARC, 2006) have meant that RT has not found general acceptance in the West. The material was popular in the Soviet Union, Eastern Europe, and several former communist countries and continues to be marketed there.[10],[11],[12] The distinct red color of the resin combined with the geopolitical origin of the material has often led to the material being referred to in the English endodontic literature as “Russian Red” cement.[5],[10],[13] The principal use of RT has been for endodontic treatment in permanent teeth, and there have been reports of pink teeth resulting from RT using RF cement.[5] The effects of RF cement on primary teeth have gone largely unreported, and the little available literature on the subject comes from the Eastern European literature.[11],[12],[14] This article reports the case of two siblings who presented to the clinic with pink discoloration of the primary teeth associated with mobility. This report highlights the toxicological methodology followed in the detection of the RF cement and histologically demonstrates the effect of RF cement on primary pulp cells.

Case Reports

A mother of a 6-year-old male and a 9-year-old female reported to a clinic in Riyadh, with a complaint of discoloration and mobility of her children's teeth. The mother reported that her children had been treated by a Ukrainian dentist and some of her children's teeth had become loose. The teeth were otherwise asymptomatic, and the children gave no history of pain or sensitivity. Written informed consent was obtained from the mother for the use of images and other diagnostic material obtained from her children for the preparation of this.

Case 1

The 6-year-old child was medically fit and healthy. On clinical examination, the left upper primary molars, all lower primary molars and the right upper second molar and upper left first primary molar (tooth number 55, 64, 74, 75, 84, and 85) showed a pinkish hue [Figure 1]a and [Figure 1]b. The affected teeth had red intrinsic discoloration with red stained margins around previously placed restorations [Figure 1]a and [Figure 1]b. Periapical radiographs revealed radiolucency extending from the furcation area to beyond the apex of the affected teeth [Figure 2]a. All affected teeth exhibited Grade III mobility and were indicated for extraction. The affected teeth were extracted, and on extraction, red discoloration of the cementum was observed [Figure 2]b. A long-span band and loop space maintainer were placed in the lower, while a nance palatal arch space maintainer was placed in the upper arch.

Figure 2: (a) Periapical radiograph of patient one showing radiolucency surrounding tooth number 84 and 85 of patient one. (b) Reddish discoloration of the roots observed in the roots of the extracted teeth

A 9-year-old female (sister of case 1) presented with a complaint of discoloration of the teeth [Figure 1]c and [Figure 1]d. Her sibling had a similar discoloration in his teeth. On examination, the upper and lower right first primary molar (tooth number 64 and 85) showed clinical Grade II mobility. As with her sibling, previous restorations were present on the affected teeth, and the borders of the filling exhibited reddish discoloration. The affected teeth were extracted, and although the roots were resorbed, a pink band was visible in the area of the cementoenamel junction with the reddish discoloration extending onto the cementum.

Given the age of the patient, no space maintainer was placed, and the patient followed up for observation.

Histological and toxicological examination

One extracted tooth from each patient was set aside for histological examination by an oral pathologist, while two teeth (one from each patient) were set aside for mass spectrophotometric analysis by a toxicologist.

The teeth were decalcified in a working solution of 8% hydrochloric acid and 8% formic acid for 20 days and embedded in paraffin wax. The teeth were then sectioned using a microtome and stained with routine hematoxylin and eosin staining. Histological examination showed molars with the remnant of the pulp chamber that contained debris of filling material and degenerate tags of pulp tissue [Figure 3]a. There were “ghost” odontoblasts and fibroblasts present in the radicular portion of the first patient indicating coagulative necrosis suggestive of an attempted a pulpotomy [Figure 3]b. The dentinal tubules appeared to be clear and did not show signs of infiltration by the filling material. No differences were observed in the histological picture of either patient, except that fewer cells were observed in the tooth from the older child.

Toxicological analysis was performed by injecting a prepared sample of the remnants of the dental pulp into a gas chromatography-mass spectrometry (GC-MS) system (TRACE™ Ultra, Thermo Fisher Scientific, Waltham MA, USA). The spectrometry was run in the electron impact mode with an electron energy of 70eV (mass 0.32 mm, range 25–700 mHz). A capillary column low-bleed CP-Sil 8 CB-MS (30 m of 0.25 μm film thickness of coated material) was used. The injector was set at 280°C and the detector at 290°C. GC was performed in the splitless mode with 1 min splitless time. The temperature program which is laboratory specific system was used. The flow rate of carrier gas (helium) was maintained at 1.9 mL/min. Identification of compound was obtained by comparing the retention times with those of standard compound, and the spectral data obtained from the Wiley and NIST combined mass spectral library (http://www.mswil.com/software/mass-spectrometry-libraries/wiley-nist). While the analysis showed a definitive confirmation of resorcinol, the formaldehyde and resin were not present in adequate concentration for definitive confirmation [Figure 4]. Similar patterns were observed in the pattern of both children.

The movement of dentists across borders in the 21st century has led to several associations emphasizing the necessity to standardize teaching curricula. Despite the attempts at standardization, dental products from the erstwhile Soviet Union and Eastern Europe receive little attention in the English language endodontic literature. RF cement, also referred to as “Russian Red” cement, is one such material. In this case, apart from the red color of the teeth, the knowledge that the child was treated in Ukraine was a reason to suspect RF cement as a cause for the discoloration.

GC-MS is a commonly used tool in toxicology laboratories world over. It is often used in forensic pathology to confirm the source and composition of unknown substances.[15] The technique has been shown to be a useful tool in determining the chemical composition of dental materials.[16] While GC-MS is not readily available to dentists in a clinical setting, the technology is available in most forensic pathology laboratories. In this case, GC-MS was not used as a routine clinical test but rather to conclusively determine the presence of resorcinol. The fact that only a resorcinol spike was observed in the GC-MS reading could be explained by the fact that the high temperatures used for the preparation of the extract would result in the hydrolysis of volatile compounds such as formalin or the RF resin.[17]

RT in general and RF, in particular, have been reported to have higher incidences of postendodontic flare-up in permanent teeth.[13] Despite the problems reported with the cement, the cement continues to be marketed in Eastern Europe (Foredent™, SpofaDental, Jičín, Czech Republic). The lack of literature regarding RF cement has meant that little is known about indications or contraindications in primary teeth. Apart from a study cited by Schwandt and Gound (2003), the authors were unable to find evidence to support the use of FS in primary teeth (Indzova and Hajduska, 1983). The cases reported here highlights the dangers of substituting materials intended for use permanent teeth, in primary teeth.

The changes to the permanent dental pulp due to RF have been histologically evaluated;[8] however, there is little known about histological changes in the primary teeth. The histological sections of the two cases reported here confirm the findings of Sikri et al. that RF causes coagulative necrosis of the pulp. However, the penetration of RF into the radicular dentinal tubules, reported in permanent teeth, was not evident in either sample.[8] While the pathway of leakage of the formocresol may be assumed to be the furcation area, there is insufficient evidence in the two cases reported here to make a definitive conclusion.

There have been concerns raised over the increasing rise in patients crossing borders to seek cheaper dental care or medical care.[18],[19] Eastern Europe has emerged as a popular destination for what has been termed as “dental tourism.”[20] The cases reported here raise the real possibility of the dentist being faced with materials that are not available or taught in their own country. Endodontists, pediatric, dentists, and general practitioners need to be aware of the possible dangers of the use of RF in the primary teeth.

Conclusion

RT with RF is a technique that continues to be practiced in some parts of the world. The cases reported here suggest that RF can not only result in discoloration of the primary teeth but may also aggravate the periradicular condition resulting in tooth mobility and early extraction. Given the increasing trend of patient's traveling abroad for dental treatment, practitioners need to be aware of the dangers of the use of RF in primary teeth.

Declaration of patient consent

The authors certify that they have obtained all appropriate patient consent forms. In the form the patient(s) has/have given his/her/their consent for his/her/their images and other clinical information to be reported in the journal. The patients understand that their names and initials will not be published and due efforts will be made to conceal their identity, but anonymity cannot be guaranteed.